How to solve the value error received while working with this dictionary?

I have a dataframe from which the columns are grouped as:

{(a, b, c): [('d', e, f)]}

with this command:

dct = df.groupby(['a','b','c'])[['d','e','f']].apply(
            lambda g: list(map(tuple, g.values.tolist()))).to_dict()

After this, I apply:

dct = {k: dict(v) for k,v in dct.items()}

which gives me the following error:

ValueError: dictionary update sequence element #0 has length 3; 2 is required

I want to make a dictionary in following format.

{(a,b,c):{d:(e,f)}}